package org.springframework.boot.context.properties.source;

import org.springframework.core.env.EnumerablePropertySource;
import org.springframework.core.env.PropertySource;

import java.util.List;
import java.util.function.BiPredicate;

/**
 * Strategy used to provide a mapping between a {@link PropertySource} and a
 * {@link ConfigurationPropertySource}.
 * <p>
 * Mappings should be provided for both {@link ConfigurationPropertyName
 * ConfigurationPropertyName} types and {@code String} based names. This allows the
 * {@link SpringConfigurationPropertySource} to first attempt any direct mappings (i.e.
 * map the {@link ConfigurationPropertyName} directly to the {@link PropertySource} name)
 * before falling back to {@link EnumerablePropertySource enumerating} property names,
 * mapping them to a {@link ConfigurationPropertyName} and checking for applicability. See
 * {@link SpringConfigurationPropertySource} for more details.
 *
 * @author Phillip Webb
 * @author Madhura Bhave
 * @see SpringConfigurationPropertySource
 */
public interface PropertyMapper {

    /**
     * The default ancestor of check.
     */
    BiPredicate<ConfigurationPropertyName,ConfigurationPropertyName> DEFAULT_ANCESTOR_OF_CHECK =
            ConfigurationPropertyName::isAncestorOf;

    /**
     * Provide mappings from a {@link ConfigurationPropertySource}
     * {@link ConfigurationPropertyName}.
     * @param configurationPropertyName the name to map
     * @return the mapped names or an empty list
     */
    List<String> map(ConfigurationPropertyName configurationPropertyName);

    /**
     * Provide mappings from a {@link PropertySource} property name.
     * @param propertySourceName the name to map
     * @return the mapped configuration property name or
     * {@link ConfigurationPropertyName#EMPTY}
     */
    ConfigurationPropertyName map(String propertySourceName);

    /**
     * Returns a {@link BiPredicate} that can be used to check if one name is an ancestor
     * of another when considering the mapping rules.
     * @return a predicate that can be used to check if one name is an ancestor of another
     */
    default BiPredicate<ConfigurationPropertyName,ConfigurationPropertyName> getAncestorOfCheck() {
        return DEFAULT_ANCESTOR_OF_CHECK;
    }
}
